Turbine blading



7, R c ALLEN E AL TURBINE BLADING Filed May 8, 1939 2 Sheets-Sheet l EIf v April 7, 1942.

R. c. ALLEN ET AL TURBINE BLADING Filed May 8, 1939 2 Sheets-Sheet 2 IIu m Patented Apr. 7, 1942 TURBINE BLADING Robert 0. Allen, Wauwatosa,and James Wilson, West Allis, Wis., assignor to Allis-ChalmersManufacturing Company, Milwaukee, Wis., a

corporation of Delaware Application May 8 1939, Serial No. 272,414

12 Claims.

defining surfaces disposed in nested or in par tially nestedrelationship. The driving fluid is applied intermittently by means ofcircumferentially spaced nozzles or groups of nozzles and the drivingfluid subjects the blades to forces that may amount to many hundreds ofpounds per blade. Consequently, when blades of great ,relative width areemployed under conditions of high rotative speed and high temperatureand pressure, the use of circumferential retaining grooves becomesimpractical because of the great axial width of the retaining rims atthe sides of the grooves and also because of the great dimculty ofproviding a suitable closing or locking device for holding the lastblade in place.

The usual practice is to enlarge the circumferential retaining groove atone or more points to permit the insertion and removal of the blades andthe last'blade or blades to be inserted are secured in position by meansof suitable wedging and locking members. Enlarging the circumferentialretaining groove materially weakens the rim portions of the groove inthe region of the enlargement and the high bending moments set up by theintermittent application of thedriving fluid renders the obtainment of astable structure highly impractical. In fact,

there is no known manner of inserting and se-\ curing the last blade ina circumferential blade retaining groove which is practical and whichwill permit the use of highly emcient passages under conditions ofmaximum capacity and maximum temperature.

It is therefore an object of this invention to provide a novel bladeassembly wherein each blade of a circumferential blade row in which thespaced concave convex passage defining surfaces on adjacent blades aredisposed in nested or in partially nested relationship, is secured tothe turbine spindle in exactly the same manner.

Another object of this invention is to provide a novel blade assemblywherein the blades coacting to form a c rcumferential blade row, in

which the spaced concave convex passage de- Q fining surfaces onadjacent blades are disposed in nested or in partially nestedrelationship, are mounted in a circumferential row of spaced axiallyextending grooves.

Still another object of this invention is to providea novel bladeretaining grooving arrangement for turbine spindles.

A further object of this invention is to provide a novel method ofinserting blades in a turbine spindle to form a circumferential bladerow in which the spaced concave convex passage defining surfaces onadjacent blades are disposed in nested or in partially nestedrelationship.

The invention accordingly consists of the method of blade insertion andof features of construction, combinations of elements, and 'arrangementof parts as more fully pointed out in the appended claims and in thedetailed description in which:

Fig. l is a partial sectional view of the turbine embodying theinvention;

Fig. 2,is a sectional view of a portion of the turbine spindle taken online 11-11 of Fi 1;

Fig. 3 is a view taken on line IIIIII of Fig. 1 with a portion of theshrouding broken away to show the cross-sectional configuration of theblades and fluid passages;

Fig. 4 is a bottom plan view of'the blades for a circumferential bladerow disposed in cooperative relationship about a circular form;

Fig. 5 is a plan view of a form having grooves conforming with the axialgrooves in the turbine spindle;

Fig. 6 shows the blades assembled in their proper cooperativerelationship with respect to the forms shown in Figs. 4 and 5, the formsbeing shown in section;

Fig. '7 is a vertical section through a portion of the turbine spindleand a hydraulic press' for simultaneously inserting a circumferentialrow of blades in their respective spindle grooves;

Fig. 8 is a plan view of a form used for come pleting the insertion ofthe blades in the spindle grooves: and

Fig. 9 is a central vertical sectional view of the form shown in Fig. 8.The turbine, reference being had to Fig. 1, comprises a spindle i havingtwo circumferentially extending rows of blades 2 and 3, which rows areaxially spaced apart to cooperatively receive therebetween a row ofstationary blades & secured to the casing 6 in a conventional manner.The blades are prevented from moving in a lateral direction with respectto the circumferential blade rows by means of spacing blocks 1 and theconventional locking groove and ring arrangements 8. The casing 6 isprovided with for an understanding of the invention; have been omittedto simplify the disclosure. The blades 2 and 3 forming thecircumferential blade row's 2 each have, as best shown in ms." 2 and a,a 'root portion il, a'body portion II, a passage defining portion l2presenting opposed concave convex passage defining surfaces i4 and i6,respectively. andan integral shroud portion II. The concave surface N onone blade coacts with the convex surface I of the next adjacent blade toformtherebetween -a pe ll for the driving fiuid. The blades 2 define thepassage II by having the coacting concave convex surfaces on adjacentblades disposed in partially nested relationship whereas thecorresponding passage defining surfaces of the blades 3 are not disposedin partially nested relationship. Due to this difference inconstruction, the abutting side surfaces of the shrouds l1 and of thebody portions I2 01' the blades 3 are plane surfaces whereas thecorresponding surfaces of the blades 2 are curved.

The blade pitch is essentially the same in both of the circumferentialblade rows and whether the coacting concave convex passage definingsurfaces on adjacent blades are disposed in partially nestedrelationship is determined by the inlet and outlet angles of the bladesand by the widthof the fluid passage. v

As shown in Fig. 3,the dividing line between adjacent blades as definedby the curved abutting side surfaces 'of the shrouds II and the.

body portions l2 of the blades 2 does not coincide with concave fluiddriving surfaces I 4. This ar- -rangement provides a fiuid confiningpassage which is sealed at the outer and inner boundaries defined by thecoacting concave convex surfaces l4 and I6, respectively. The fiuidpressure within the passage is greatest at the outer and-innerboundaries and with this construction, it is not fecting centrifugalstability as the center or! a gravity and the line of action-of the.centrifugal force is thereby displaced in a direction such that thedesired centrifugal moment may be obtained with a blade having lessmass.

The spindle I, reference beinghad to .Figs. 1 through 3, has acircumferential groove ll approximately equal in width to the distancethe blade roots are spaced apart to form the axially spacedcircumferential blade rows and a circumferential row of spaced axiallyextending blade retaining grooves 2| of greater depth than thecircumferential groove I2. The axial grooves 2| extendlaterally beyondthe sides of the circumferential groove is distances approximately equalto the axial length of the root portions ll of the blades 2 and 3.

the root portions ii of the blades 2 and 3 and of the spacing block Iare slotted as shown in Fig. 2 to provide mutually coasting retainingsurfaces 22. The relative depth of the grooves I! and 2| should be suchthat the portion of the walls of the grooves 2| which lie below thebottom surface of the groove I! present retaining surfaces effective to.secure the spacing block I against movement in a radial direction.

The best procedure to follow in order to obtain the previously describedarrangement of grooves is to first cut the circumferential groove I, thecross-sectional configuration of which is preferably rectangular andthen to cut the axial retaining grooves 2|. This procedure enables ea hof the axial retaining grooves all to be made with a single breachingoperation thereby materiali reducing the time required and-the.machining 4 costs. The concave convex passage defining surfaces II andI! and the root portion. of each of the blades 2 and 8 are accuratelymachined and finished.as is also the same one side surface of each bladeas defined by the side surfaces of the body and shroud portions l2 andI1 respectively whichare adapted to abut the body and shroud portions ofthe next adjacent blade. The opposite side of each blade is machined tothe approximate dimension desired there being excess material left onthis side which is removed whenthe blades are fitted.

Each blade after being machined as previof the distance between asurface of the measur- I ing device and the accurately machined side ofthe blade. This measurement accurately determines the material to bemachined from the unfinished side of the blade which is to be insertedin the groove containing the measuring device. The blade and the groovein which the blade was partially inserted are marked for futureidentification and this blade and the measuring device are then removed.A blade is then selected for insertioninthe groove from which themeasuring device was removed and is marked for further machining asindicated by the measurement previously taken. This blade'and themeasuring been measuredand identified with respect to the The walls 'ofthe axial grooves 2| and the corresponding side walls of grooves inwhich the blades are to be inserted in their proper cooperativerelationship. The unfinished sides of the blades are then machinefinished as indicated by the measurements.

The blades for the first circumferential bladerow in which the fiuidpassages it are defined by having the coacting cocave convex surfaces onadjacent blades disposed in partially nested relationshipas representedby the blades 2 in Fig. 3 must now be inserted in their respectivegrooves in pairs to determine whether further hand fitting is necessary.A pair of blades previously fitted with respect to one another as abovedescribed are held together in proper cooperative relationship and anattempt is made to simultaneously insert the blades in their respectivegrooves. The proper grooves can be readily idenseparately inserted andfitted in the usual manferential blade row have been finally fitted,the.

diameter of the spindle I measured at the bottom of the axial grooves 2|and the blades may be arranged in their proper cooperative relationshipwith their roots contacting the form 24 as shown in Figs. 4 and 6 bymoving the individual blades in a radial direction with respect to theform 24. Any suitable means such as the flexible band 26 may be placedabout the blades as shown in Figs. 4 and 6 and tightened to hold theblades in position against the form 24. It should be understood that thearrangement of the blades about the form 24 as previously described iseffected on a table or other suitable supporting surface 21 (Fig. 6).The form 24 has an annular, coaxially extending guide member 28 and thethickness of the form 24 is preferably considerably less than the axiallength of the blade roots H as shown in Fig. 6.

The outer periphery of the annular form 29- shown in Fig. has slottedblade retaining spaced bolt holes 44 equal in number and arranged foralinement with the threaded holes 32 in form 29. The side wall ofthe'cylindrical.

member 4| is provided with openings 43 for inserting cap screws into theholes 44 in the face plate 43 which enables the form 29 to be rigidlysecured to the annular face plate 43 of the cylindrical member 4| bymeans of cap screws 41 as shown in Fig. 7. Fluid for operating the pressis admitted and drained from opposite sides of the piston .31 as desiredby means of the pipes and ports 48 and 49, respectively.

The form 29 with blades 2 mounted thereon 'aspreviously described isattached to the face plate 43 .by means of the cap screws 41. Thespindle is supported in any suitable manner 'such as by means of a crane(not shown) and the spindle and press are brought into the cooperat-iverelationship shown in-Fig. '7 with the end.

of the spindle shaft extending within the hollow cylindrical member 4|in coaxial alinement with the cylinder 36 of the press 33 so that thecylindrical member 4| may be reciprocated in coaxial alinement withrespect to the spindle and grooves 3| which are identical incross-sectional configuration, arrangement and number to the axialgrooves 2i in the spindle The form 29 also has a plurality ofcircumferentially spaced threaded holes 32 located on a circleconcentric with respect to the center of the form. The inside diameterof the form 29 is greater than the diameter of the spindle shaft asshown inFig. '7 and substantially equal to the outside diameter of theannular guide member 28 on the form 24. The guide member 28 serves tocenter the form 29 with respect to the form 24 as shown in Fig. 6. Afterthe blades have been arranged about the form 24 and secured thereto asdescribed in the preceding paragraph, the form 29 is placed upon theform 24 to effect the relationship shown in Fig. 6 with that portion ofthe roots of the blade which extend above the form 24 disposed in thegrooves 3| of the form 29. The roots of the blades fit the grooves 3| inthe form 29 with suflicient snugness so that when the retaining band 726 is loosened, the form 29 and the blades 2 may one another andall'that remains to be done isto so position the form 29 with respect tothe spindle I that the roots of the blades are in axial alinement withthe corresponding grooves 2| and' to' simultaneously insert the roots ofthe blades in their respective grooves. Apparatus suitable forsimultaneously pressing the blades into their respective grooves isshown in Fig. '7 and comprises a hydraulic press 33 having a base 34, acylinder 36 containing an actuating piston 31 and a guide portion 38, apress plate 39 formed integral with the guide portion 38, and a hollowcylindrical member 4| of welded construction which is removably securedto the press plate 39 by means of bolts 42. The end of the cylindricalmember 4| opposite the end secured to the press plate 39 consists of anannular face plate 43 having an inside diameter greater than that of thespindle shaft and circumferentially the axial grooves 2|. The roots H ofthe blades 2 may then be readily brought into axial alinement with theirrespective grooves in the spindle by rotating either the spindle i orthe cylindrical member 4| with respect to the press face plate 39. Inthe arrangement shown, the blade roots II and the grooves 2| are broughtinto proper alinement by slowly rotating the spindle i, which is heldagainst axial movement in a direction away from the press by a fixedmeans 5|, in any desired manner. When the blade roots II and the grooves2| are properly alined, the press 33 is operated to move the form 29towards the spindle and the blades are simulta neously pressed intotheir respective grooves until the form 29 abuts the side of the spindleI. The cap screws 41 which secure the form 29 to the face plate 43 arethenremoved and if the flexible retaining-band 26 has not already beenremoved, it is removed at this time. The press is then operated to movethe face plate 43 away from the spindle I which leaves the form 29suspended on the spindle I by means'of the blades 2.

Fi s. 8 and 9 show an annular form 52 which is adapted to be secured tothe face plate 43 in order to. completely insert the blade roots intothe grooves 2|. One side of th s form is provided adjacent its outerperiphery with a circular row are preferably defined by radial planesand their circ mferential width is such that when the projections 53 aremoved axially into the grooves 2|. the plane side'surfaces of theprojections will cooperate with the walls of the grooves and prevent thprojecti ns from bending. The radial len th f the projections 53 shouldapproximately efllial the radial depth of the grooves 2|, but in n eventshould the diameter of the circle defi ed by the inner ends of theseprojections be into the grooves 2|. Form 52 is provided withthreadedbolesllarrangedtoalinewiththeholes proper position within thegrooves II. The press V is then operated to-withdraw the face plate 43from the vicinity of the spindle, the forms fl and I! are removed, andthe locking arrangement 8 applied to secure the blades against lateralmovement with respect to the circumferential blade row. If the blades 8and the spacing blocks I were inserted before the blades 2 nothingfurther remains to be done, but it may be desirable to insert thespacing blocks I and the blades 3 after the blades 1 have been inserted.This may be done with the arrangement shown as the spacing blocks I andthe blades I can be separately inserted at the opposite end of thegrooves 2|. Obviously, if the operating pressures, temperatures. etc.dictate theme of blades in the second circumferential blade row havingcoacting concave convex passage defining surfaces disposed in partiallynested relationship, these bladesowould be simultaneously inserted inthe manner described with respect to the blades 2. In this event, theblades forming the secondcircumferential blade row would be insertedfirst. I I

The use of a hydraulic press or any other suitable type of machine forforcing the blades into thegroovesisnotessentialasthebladesmaybemanually inserted by using the types of forms disclosed or anyothersuitable means on which the blades can be arranged in their proper co-'operative relationship, retained in this position. and the rootssimultaneously inserted in their respective grooves. In this connection,it should be obvious that the cross-sectional configuration of the bladeroots and of the retaining grooves may be varied as desired. Theinvention is ob.-

viously applicable to all types of turbines in which one. or morecircumferential blade rows are formed byblades having coacting concaveconvex passage defining surfaces disposed in 'a circumferential row ofspaced axially extending side entry retaining grooves, thecross-sectional configuration of which conforms with that of the bladeroots, with the opposed passage defining surfaces on adjacent bladesdisposed in nested or in partially nested relationship which comprisesfitting the blades to obtain the necessary cooperative relationshipbetween coactingsur-' faces on adjacent blades, placing theblades'together in their proper cooperative relationship and securingthe blades in this position, moving the blades thus secured togetherinto a position such that the root portion of each blade isin ouslyinserting the roots of the individual blades into the axial retaininggrooves.

2. The method of 'assemblingturbine blades in a circumferential row ofspaced axially extending side entry retaining grooves, thecross-sectional configuration of which conforms with that of the bladeroots. with the opposed passage defining surfaces on adjacent bladesdisposed in nested orin partially nested relationship which comprisestion of each blade is in substantial axial alinement with a groove inthe circumferential groove row, and simultaneously inserting the rootsof the individual blades into'theaxial retaining grooves.

-3. The method of assembling turbine'blades in a circumferential row ofspaced axially extending side entry retaining grooves, the crossshipwhich comprises simultaneously inserting a substantial axial alineinentwith a groove in pair of adjacent blades into adjacent grooves in thecircumferential row, fitting the blades to obtain the necessarycooperative relationship between coacting surfaces and then removing theblades from the grooves,repeating this operationusingpairsofblade'sconsistingofoneblade of the pair previously fitted and the nextadjacent blade until all blades have been inserted' in their respectivegrooves and fitted with respect-to adjacent blades, placing thebladea'together in their proper cooperative relationship and securingthe blades in this position. moving the blades thus secured togetherinto a position such that the root portion of each blade is insubstantial axial alinement with the corresponding groove in thecircumferential groove row, and

simultaneously inserting the roots of the individual blades into thecorresponding axial retaining grooves. I

4. A moving blade assembly for elastic fluid turbines comprising aspindle having a circumferential row of spaced axially extending andsubstantially straight side entry blade retaining grooves, a bladesecured in each groove, said blades each including a convex and aconcave fluid directing side surface, and said grooves and blades beingso constructed and arranged that the convex side surface on each bladeis disposed in partially nested passage defining relation with respectto the concave side surface on the next adjacent blade.

5. A moving blade assembly for elastic fluid turbines comprising aspindle having a circum ferential row of spaced axially extending andsubstantially straight side entry blade retaining grooves each of whichis of suilcient length to retain two blades in axially'spaced relationsuch that the blades in the circumferential row of axially extendinggrooves coact andform axially spaced circumferential blade rows adaptedto receive therebetween a circumferential row of stationary blades, twoblades secured in each groove in axially spaced blade row formingrelation,

said blades each including a convex and a concave fluid directing sidesurface, and said grooves and blades being so constructed and arrangedthat the convex side surface of each blade in one circumferential bladerow is disposed in partially nested passage defining relation withrespect to the concave side surface on the next adjacent blade insaid-one row.

' 6.' A moving blade assembly for turbines in which circumferentialblade rows are axially spaced to receive therebetween a circumferentialrow of stationary blades comprising a spindle having a circumferentialgroove approximately equal in width to the distance the blade roots areto be spaced apart to form the axially spaced blade rows, acircumferential row of spaced axially extending side entry retaininggrooves each of which is of greater depth than said circumferentialgroove and extends laterally beyond the sides thereof thereby providingaxially spaced blade root retaining portions, two blades in each axialgroove having their root portions secured in said spaced blade rootretaining portions and forming axially spaced circumferential bladerows, and means including a spacing block disposed in that portion ofeach axial groove which is below and merges with the bottom portion ofsaid circumferential groove operable to prevent movement of the bladeslongitudinally of the axial retaining grooves.

7. A moving blade assembly providing axially spaced, circumferentialblade rows adapted to cooperatively receive therebetween a circumfereential row of stationary blades comprising a spindle having acircumferential groove approximately equal in width to the axialdistance the blade roots are to be spaced apart to form the axiallyspaced blade rows, a circumferential row of spaced axially extendingside entry retaining grooves each of which is of greater depth than saidcircumferential groove and extends laterally beyond the sides thereof, aspacing block disposed in that portion of each axial groove which v isbelow and merges with the bottom portion of row of spaced axiallyextending side entry retaining grooves each of which is of greater depthprising a circumferential groove approximately equal in width to thedistance the blade roots are to be spaced apart to form the axiallyspaced blade rows, and a circumferential row of spaced axially extendingside entry retaining grooves each of' which is of greater depth thansaid circumferential groove and extends laterally beyond the sidesthereof distances approximately equal to the axial length of the=rootportions of the blades adapted to be "secured therein thereby providingaxially spaced blade root retaining portions and an intermediate spacingblock retaining portion.

10. A turbine spindle having means for re-' taining blades incircumferential rows axially spaced apart to cooperatively receivetherebetween a circumferential row of stationary blades comprising acircumferential groove approximately equal in width to the distance theblade roots are to be spaced apart to form the axially spaced bladerows, and a circumferential row of spaced axial side entry retaininggrooves each of which is of greater depth than said circumferentialgroove and extends laterally beyond the sides thereof distances,approximately equal to the axial length of the root portions of theblades adapted to be secured therein, said axial grooves each havingtheir side surfaces including the portions which are below and mergewith the bottom of the circumferential groove slotted to provideretaining surfaces. 7

11. A turbine spindle having means for retaining blades with rootportions presenting opposed multiple slotted retaining surfaces incircumferential rows axially spaced apart to cooperatively receivetherebetween a circumferential row of stationary blades comprising acircumferential groove approximately equal in width to the distance theblade roots are to be spaced apart to form the axially spaced blade rowsand of a depth less than that of the blade roots by at least the widthof a retaining slot, and a circumferential row of spaced axiallyextending side entry retaining grooves each of which has across-sectional configuration conforming with that of the blade rootsand each of which extends laterally beyond the sides of saidcircumferential groove distances approximately equal to the length ofthe root portions of the blades to be secured therein.

12. A turbine spindle having means for retaining blades with rootportions presenting opposed multiple slotted retaining surfaces incircumferential rows axially spaced apart to cooperatively receivetherebetween a circumferential row, of stationary blades comprising acircumferential groove approximately equal in width to the distance theblade roots are to be spaced apart to form the axially spaced blade rowsand of a depth less than that of the blade roots by at least the widthof a retaining slot, and a circumferential row of spaced axiallyextending side entry retaining grooves each of which has a depthconforming with that of the blade roots and each of which extendslaterally beyond the sides of said circumferential groove distancesapproximately equal to the axial length of the root portions of theblades to be secured therein, said axial grooves including the portionbelow the bottom of the circumferential groove having slotted retainingsurfaces adapted to coact with the slotted retaining surfaces of theblade roots.

. ROBERT C. AILEN.

JAMES WILSON.

